1. Field of the Invention
The present invention relates laser printers and particularly to configurations for grounding the laser printer's diselectrification brush.
2. Description of the Background Art
A laser printer arranges toner on a surface of a photoreceptor drum charged by laser light and sandwiches a sheet between the photoreceptor drum and a transfer roller to place the toner on a surface of the sheet or the like in a shape to be transferred. The toner placed on the surface of the sheet or the like is fixed on the sheet or the like by a fixture roller and thus discharged.
The sheet or the like having passed between the photoreceptor drum and the transfer roller is statically charged. To remove the static electricity, a diselectrification brush diselectrifying the sheet or the like is arranged adjacent for example to the sheet or the like output through between the transfer roller and the photoreceptor drum.
For example Japanese Patent Laying-Open No. 9-114277 discloses a transfer apparatus having a diselectrification needle arranged in a prescribed diselectrification region to achieve the needle's significant diselectrification effect. As disclosed in the document, if in this transfer apparatus the apparatus's cover attached disadvantageously clatters, a spring contact's resilience can compensate for the clatter to allow the needle and a transfer nip to have a fixed relative positional relationship therebetween.
Furthermore FIG. 7 shows a cross section of an image formation apparatus disclosed in Japanese Patent Laying-Open No. 2001-154495. A sheet or the like is transported along a transport path 72 in a direction 61. The sheet or the like is sandwiched between a transfer roller 51 and a rotation roller 52 and thus transported. Around transfer roller 51 is arranged a transport guide 57 with a control member 54 joined thereto.
A diselectrification brush 53 is joined to control member 54, and control member 54 is connected to a plate 60 via an extension contact 55 and a ground plate 56. By grounding plate 60, diselectrification brush 53 provides diselectrification. The member contacting and thus controlling the brush's bristles is adapted to be conductive to allow the bristles to be grounded to ensure that the bristles are grounded and a material receiving what is transferred is diselectrified, as described in the document.
A diselectrification brush is used to diselectrify sheets or the like. If the sheet or the like is not diselectrified, the sheet or the like is disadvantageously attracted to the photoreceptor drum. More specifically, the sheet or the like does not readily come off the photoreceptor drum and is not transported smoothly. Furthermore, if the charged sheet or the like is continuously transported, the sheet being transported is disadvantageously attracted by other components. In other words, the performance of transporting the sheet is impaired. Accordingly, diselectrification of the sheet or the like must be ensured at a transport path immediately following the photoreceptor drum.
Japanese Patent Laying-Open Nos. 9-114277 and 2001-154495 disclose apparatuses provided with a diselectrification brush for diselectrification. However, they disadvantageously have a complicated mechanism to ground the diselectrification brush. Furthermore, they have a large number of components resulting in poor productivity.